Control device



I March 17, 1942. c CLARE ETAL 7 2,276,535

CONTROL DEVICE Filed Sept. 30, '1938 Fig: 5

INVENTORS Carl F. Clare Y Irvin IILL Bax ATTORNEYS Patented Mar. 17, 1942 STATES PATENT OFFICE CONTROL DEVICE tion of Delaware Application September 30, 1938, Serial No. 232,646

6 Claims.

The present invention relates to control devices and more particularly to improvements in control devices of the polarized electromagnetic type.

It is an object of the present invention to provide an improved electromagnetic control device of the polarized type which is of rugged and economical construction and which operates in a reliable and positive manner.

Another object of the invention is to provide a polarized electromagnetic control device comprising a magnetic field structure including a permanent magnet, which embodies an improved. arrangement for preventing demagnetization of the permanent magnet during the course of operation thereof.

A further object of the invention is to provide a polarized electromagnetic control device comprising a magnetic field structure including an armature movable between a normal position and an operated position and an operating Winding for controlling the position of the armature, which embodies an improved arrangement utilizing a permanent magnet for returning the armature to its normal position subsequent to the operation of the device.

In brief, the objects set forth above are in part realized in accordance With one feature of the present invention by providing a control device comprising a magnetic field structure having an operating Winding electromagnetically associated therewith and including a field element, a movable armature element associated with the field element and a permanent bar magnet carried by one of the elements, wherein the one element and the permanent magnet carried thereby are so constructed and arranged that the portion of the one element adjacent the permanent magnet positively prevents demagnetization of the permanent magnet when the operating winding is energized to produce a magnetic flux in the one element which is in opposition to the magnetic flux produced therein by the permanent magnet. In accordance with one embodiment of the invention, the permanent magnet is directly secured to the armature element; and in accordance with another embodiment of the invention, the permanent magnet is directly secured to the field element.

In accordance with another feature of the invention, the field structure includes first and second field elements, a permanent magnet and an armature element movable between the field elements; and operating and polarizing windings are electromagnetically associated with the field structure. The field structure is so constructed and arranged that the armature element is normally biased toward the second field element and is moved toward the first field element when the operating winding is energized with current of one polarity; and that the armature is returned toward the second field element by an arrangement including the permanent magnet when the operating winding is deenergized. In accordance with one embodiment of the invention, the permanent magnet is directly secured to the armature element; and in accordance with another embodiment of the invention, the permanent magnet is directly secured to the second field element.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawing, in which Figure 1 is a side elevational View of a polarized electromagnetic control device embodying the present invention; Fig. 2 is an end elevational view of the control device shown in Fig. 1; Fig, 3 is a side elevational view of a modified form of the polarized electromagnetic control device; Fig. 4 is an end elevational View, partly broken away, of the control device shown in Fig. 3; Fig. 5 is a side elevational View of another modified form of the polarized electromagnetic control device; Fig. 6 is an end elevational view of the control device shown in Fig. 5; Fig. 7 is a side elevational view of a further modified form of the polarized electromagnetic control device; and Fig. 8 is an end elevational view of the control device shown in Fig. '7.

Referring now to Figs. 1 and 2 of the drawing, the control device there shown comprises a magnetic field structure including a field element or core Ill provided with an operating winding indicated at ll electromagnetically associated therewith and a substantially L-shaped field element [2, one leg I2a of which is secured to one end of the core by a screw 13. The other leg I21) of the field element l2 extends substantially parallel to the core i0 and carries a bracket 14 adjacent the outer end thereof, the bracket being secured to the leg l 22) by a screw 15. The bracket I4 is provided with two upwardly and outwardly extending arms I la arranged in spaced parallel relationship and between which a pin l6 extends. An armature element I1 is associated with a pole face indicated at Illa of the core l and provided with two upwardly extending arms Ila, arranged in spaced parallel relationship, which are pivotally secured to the pin 16. Also the armature l1 carries a rearwardly extending arm I8 provided with an insulating button I9 disposed on the outer end thereof, Apparatus comprising a contact spring assembly including a pair of 00- operating contact springs and 2| is secured to the leg 12b of the field element I2 by an arrangement comprising two screws 22 and a clamping washer 23. The contact springs 20 and 2! are insulated from each other and from the clamping washer 23 and the leg [2b of the field element I2 by a number of insulating plates 24, one of these insulating plates being arranged between each two of these elements.

The insulating button it disposed on the outer end of the arm N3 directly engages the contact spring 2i and is adapted to move this contact spring into engagement with the contact spring 20 in order to complete an electric circuit including the pair of contact springs 26 and 2| when the armature I? is rotated in a clockwise direction, as viewed in Fig. 1, about the pivot pin it. Also it is noted that the contact spring 2| is formed of resilient material and is biased away from the contact spring 20, thereby to interrupt the electric circuit including this pair of contact springs and to bias the armature H in a counterclockwise direction about the pivot pin l6 away from the pole face Illa into a normal position.

A permanent bar magnet 25 is directly secured in intimate contact with one edge of the armature H by an arrangement comprising a strap 26 and a screw H. The permanent bar magnet 25 is formed of a material having relatively high magnetic permeability and retentivity such, for example, as the alloys sold commercially under the names Alnico or Nipermag. The permanent bar magnet 25 is so arranged that a south pole thereof is disposed adjacent the pole face ltd of the core it and a north pole thereof is disposed adjacent the outer end of the leg l2b of the field element It.

When the control device occupies a normal or non-operated position, the armature i1 is biased away from the pole face iila of the core due to the resiliency of the contact spring 2 l. Also, the permanent bar magnet 25 sets up a magnetic flux which traverses two parallel magnetic paths. One of these parallel magnetic paths extends from the north pole of the permanent bar magnet 25 by way of a portion of the armature H, the legs lib and Na of the field element l2, the core I6 and another portion of the armature I! to the south pole of the permanent bar magnet. The other of these parallel magnetic paths extends from the north pole of the permanent bar magnet "25 by way of the adjacent portion of the armature il' to the south pole of the permanent bar magnet, this magnetic path constituting a short-circuiting magnetic path for the permanent bar magnet. It is noted that the permanent bar magnet 25 has a sufficiently high permeability that a considerable magnetic fiux traverses the first-mentioned parallel magnetic path in spite of the fact that the second-mentioned parallel magnetic path constitutes a shortcircuiting magnetic path for the permanent bar magnet.

The terminals of the operating winding ii are connected to a suitable source of direct current supply, thereby to cause this winding to be energized. When the operating winding H is thus energized, a magnetic flux is set up in the core :0 which causes the end thereof, adjacent the pole face l'ila, to assume a predetermined polarity Y and the end thereof, adjacent the leg l2a of the field element IE, to assume a predetermined Dolarit X, the polarities X and Y being respectively north and south poles when the operating winding is energized with a current of one polarity and the polarities X and Y bein respectively south and north poles when the operating winding is energized with a current of the opposite polarity. When the operating winding 2! is energized with a current of one polarity so that the polarity Y of the core It] is a north pole, a magnetic fiux traverses the field structure over a magnetic path extending from the north pole Y of the core H) by way of the armature I! and the legs lib and Na of the field element l2 to the south pole X of the core. It is noted that this magnetic flux traverses the magnetic field structure in the same direction as the magnetic flux produced by the permanent bar magnet 25. These accumulative magnetic fluxes are effective to cause the armature I! to be attracted to the pole face Illa of the core in, thereby to rotate the armature ll in a clockwise direction about the pivot pin IE. When the armature ll is rotated in a clockwise direction about the pivot pin IS, the insulating button I!) carried by the arm 18 moves the resilient contact spring 2 i into engagement with the contact spring 20, thereby to complete the electric circuit including this pair of contact springs.

On the other hand, when the operating winding l l is energized with a current of the opposite polarity so that the polarity Y of the core I0 is a south pole, a magnetic flux traverses the field structure over a magnetic path extending from the north pole X of the core H! by way of the legs l2a and lZb of the field element l2 and the armature IT to the south pole Y of the core. It is noted that this magnetic flux traverses the magnetic field structure in a direction opposite to that of the magnetic flux produced by the permanent bar magnet 25. These opposing magnetic fluxes are ineffective to cause the armature H to be attracted to the pole face lfla of the core 10. Thus, the armature H is not rotated in a clockwise direction about the pivot pin 16 to move the contact spring 2i into engagement with the contact spring 2!]. Thus, it will be understood that the control device is of the polarized type and is operative only in the event the operating winding l thereof is energized with a current of a predetermined polarity, the position of the armature I! with respect to the core [0 being controlled in accordance with the algebraic sum of the fluxes traversing these elements.

Moreover, it is noted that, when the operating winding H is energized with a current of the opposite polarity effective to cause the polarity Y of the core In to be a south pole, the magnetic flux produced thereby and traversing the armature l! of the field structure is bypassed around the permanent bar magnet 25 by way of the portion of the armature l1 adjacent the permanent bar magnet. Thus, this magnetic flux opposing the magnetic flux produced by the permanent bar magnet 25 is not forced through the permanent bar magnet. Accordingly, there is substantially no tendency for the permanent bar magnet 25 to become demagnetized, when the fluxes produced by the operating winding I l and the permanent bar magnet traverse the field structure in opposite directions or opposite each other. Hence, the portion of the armature 11 disposed adjacent the permanent bar magnet 25 is effective to prevent demagnetization of the permanent bar magnet when the operating winding I l is energized with a current of the opposite polarity effective to cause this winding to produce a flux in the field structure in opposition to that produced therein by the permanent bar magnet 25.

In Figs. 3 and 4 of the drawing a modified form of the control device is shown which comprises a magnetic field structure including a field element or core Bil provided with an operating winding indicated at M electromagnetically associated therewith and a substantially L-shaped field element 32, one leg 32a of which is secured to one end of the core by a screw 33. The other leg 32b of the field element 32 extends substantially parallel to the core 3!] and carries a bracket 3 1 adjacent the outer end thereof, the bracket being secured to the leg 3211 by a screw 35. The bracket 34 is provided with two upwardly and outwardly extending arms 34a arranged in spaced parallel relationship and between which a pin 36 extends. An armature element 31 is associated with a pole face indi cated at m of the core 30 and provided with two upwardly extending arms 31a, arranged in spaced parallel relationship, which are pivotally secured to the pin 3%. Also the armature 31 carries a rearwardly extending arm 38 provided with an insulating button 39 disposed on the outer end thereof. Apparatus comprising a contact spring assembly including a pair of cooperating contact springs 40 and 41 is secured to the leg 32b of the field element 32 by an arrangement comprising two screws 42 and a clamping washer 43. The contact springs 40 and 4| are insulated from each other and from the clamping washer 43 and the leg 32b of the field element 32 by a number of insulating plates 44, one of these insulating plates being arranged between each two of these elements.

The insulating button 39 disposed on the outer end of the arm 38 directly engages the contact spring M and is adapted to move this contact spring into engagement with the contact spring 40 in order to complete an electric circuit including the pair of contact springs 40 and 4! when the armature 3'! is rotated in a clockwise direction, as viewed in Fig. 3, about the pivot pin 38. Also it is noted that the contact spring M is formed of resilient material and is biased away from the contact spring 40, thereby to interrupt the electric circuit including this pair of contact springs and to bias the armature 37 in a counterclockwise direction about the pivot pin 36 away from the pole face 30a. into a normal position.

A permanent bar magnet 45 is directly secured in intimate contact with one edge of the leg 32b of the field element 32 by an arrangement comprising a strap 46 and a screw 41. The permanent bar magnet 45 is formed of a material having relatively high magnetic permeability and retentivity such, for example, as the alloys previously named. The permanent bar magnet 45 is so arranged that a south pole thereof is directed toward the outer end of the leg 3% of the field element 32 and a north pole thereof is directed toward the leg 32a of the field element 312.

When the control device occupies a normal or non-operated position, the armature 31 is biased away from the pole face 39a of the core 30 due to the resiliency of the contact spring 4!. Also, the permanent bar magnet 45 sets up a magnetic flux which traverses two parallel magnetic paths. One of these parallel magnetic paths extends from the north pole of the permanent bar magnet 45 by way of a portion of the leg 32b of the field element 32, the leg 32a thereof, the core 30, the armature 37 and another portion of the leg 32b to the south pole of the permanent bar magnet. The other of these parallel magnetic paths extends from the north pole of the permanent bar magnet 45 by way of the adjacent portion of the leg 3% of the field element 32 to the south pole of the permanent bar magnet, this magnetic path constituting a short-circuiting magnetic path for the permanent bar magnet. It is noted that the permanent bar magnet 45 has a suificiently high permeability that a considerable magnetic flux traverses the first-mentioned parallel magnetic path in spite of the fact that the second-mentioned parallel magnetic path constitutes a shortcircuiting magnetic path for the permanent bar magnet.

The terminals of the operating winding 3! are connected to a suitable source of direct current supply, thereby to cause this winding to be energized. When the operating winding 3! is thus energized, a magnetic fiux is set up in the core 30 which causes the end thereof, adjacent the pole face 38a, to assume a predetermined polarity Y and the end thereof, adjacent the leg 32a of the field element 32, to assume a predetermined polarity X, the polarities X and Y being respectively north and south poles when the operating winding is energized with a current of one polarity, and the polarities X and Y being respectively south and north poles when the operating winding is energized with a current of the opposite polarity. When the operating winding 3| is energized with a current of one polarity so that the polarity Y of the core 32] is a north pole, a magnetic fiux traverses the field structure over a magnetic path extending from the north pole Y of the core 3% by way of the armature 31 and the legs 32b and 32a of the field element 32 to the south pole X of the core. It is noted that this magnetic fiux traverses the magnetic field structure in the same direction as the magnetic flux produced by the permanent bar magnet 45. These accumulative magnetic fluxes are effective to cause the armature 3'! to be attracted to the pole face 38a of the core 3? thereby to rotate the armature 3'! in a clockwise direction about the pivot pin 36. When the armature 31 is 1'0- tated in a clockwise direction about the pivot pin 36, the insulating button 3% carried by the arm 38 moves the resilient contact spring M into engagement with the contact spring 40, thereby to complete the electric circuit including this pair of contact springs.

On the other hand, when the operating winding 3| is energized with a current of the opposite polarity so that the polarity Y of the core 35 is a south pole, a magnetic fiux traverses the field structure over a magnetic path extending from the north pole X of the core 38 by way of the legs 32a and 32b of the field element 32 and the armature 37 to the south pole Y of the core. It is noted that this magnetic flux traverses the magnetic field structure in a direction opposite to that of the magnetic flux produced by the permanent bar magnet 45. These opposing magnetic fluxes are ineffective to cause the armature 3! to be attracted to the pole face a of the core 30. Thus, the armature 37 is not rotated in a clockwise direction about the pivot pin 36 to move the contact spring 4! into engagement with the contact spring 46. Thus, it will be understood that this control device is of the polarized type and is operative only in the event the operating winding 3| thereof is energized with a current of a predetermined polarity, the position of the armature 31 with respect to the core 30 being controlled in accordance with the algebraic sum of the fluxes traversing these elements.

Moreover, it is noted that when the operating winding 3| is energized with a current of the opposite polarity effective to cause the polarity Y of the core 30 to be a south pole, the magnetic flux produced thereby and traversing the leg 32?) of the field element 32 of the field structure is bypassed around the permanent bar magnet by way of the portion of the leg 32b adjacent the permanent bar magnet. Thus, this magnetic flux opposing the magnetic flux produced by the permanent bar magnet 45 is not forced through the permanent bar magnet. Accordingly, there is substantially no tendency for the permanent bar magnet 45 to become demagnetized, when the fluxes produced by the operating winding 3| and the permanent bar magnet 45 traverse the field structure in opposite directions or oppose each other. Hence, the portion of the leg 32b of the field element 32 disposed adjacent the permanent bar magnet 45 is effective to prevent demagnetization of the permanent bar magnet when the operating winding 3| is energized with a current of the opposite polarity ffective to cause this winding to produce a flux in the field structure in opposition to that produced therein by the permanent bar magnet 45.

In Figs. 5 and 6 of the drawing another modifield form of the control device is shown which comprises a magnetic field structure including a field element or core Gil, a substantially U-shaped field element 6|, one leg Bla of which is secured to the core intermediate the ends thereof, and a substantially L-shaped field element 62, one leg 62a of which is secured to one end of the core by a screw 63. The other leg Gib of the field element BI is arranged in spaced relationship with respect to a pole face indicated at 60a of the core 60 and the other leg 62b of the field element 62 extends substantially parallel to the core 60 and carries a bracket 54 adjacent the outer end thereof, the bracket being secured to the leg 6% by a screw 65. The bracket 64 is provided with two upwardly and outwardly extending arms a arranged in spaced parallel relationship and between which a pin 56 extends. An armature element 61 is arranged between the pole face 683a of the core 60 and the leg Gib of the field element 6| and is provided with two upwardly extending arms 61a arranged in spaced parallel relationship which are pivotally secured to the pin 66. Also the armature 5'! carries a rearwardly extending arm 68 provided with an insulating button 69 disposed on the outer end thereof. Apparatus comprising a contact spring assembly including a pair of cooperating contact springs i0 and H is secured to the leg 62b of the field element 62 by an arrangement comprising two screws 12 and a clamping washer T3. The contact springs HI and I H are insulated from each other and from the clamping washer l3 and the leg 6% of the field element 52 by a number of insulating plates 14, one of these insulating plates being arranged between each two of these elements.

The insulating button 69 disposed on the outer end of the arm 63 directly engages the contact spring '11 and is adapted to move this contact spring into engagement with the contact spring 78 in order to complete an electric circuit including the pair of contact springs 19 and H when the armature 61 is rotated in a clockwise direction, as viewed in Fig. 5, about the pivot pin Also it is noted that the contact spring ii is formed of resilient material and is biased away from the contact spring 10, thereby to interrupt the electric circuit including this pair of contact springs and to bias the armature 61 in a counterclockwise direction about the pivot pin 65 away from the pole face 60a into a normal position.

An operating winding and a polarizing winding, respectively indicated at 15 and 16, are electromagnetically associated with the core 50, the operating winding being associated with the core 68 between the pole face 60a thereof and the leg E-la of the field element 6|, and the polarizing winding 75 being associated with the core 69 between the leg 61a of the field element 6i and the leg 52a of the field element (52.

A permanent bar magnet 11 is directly secured in intimate contact with one edge of the armature '5'! by an arrangement comprising a strap l3 and a screw lid. The permanent bar magnet ii is formed of a material having relatively high magnetic permeability and retentivity such, for example, as the alloys previously named. The permanent bar magnet TI is so arranged that a south pole thereof is disposed adjacent the pole face tea of the core iii and a north pole thereof is disposed adjacent the outer end of the leg 62?) of the field element 62.

The terminals of the polarizing winding 16 are connected to a suitable source of direct current supply, thereby to cause this winding to be energized. The polarity of this source of direct current supply is such that when the polarizing winding (ii is thus energized, a magnetic flux is set up in the core 6i! which causes the portion thereof adjacent the leg filo to assume the polarity of a north pole and the portion thereof adjacent the leg 62a to assume the polarity of a south pole, thereby to cause a magnetic flux to traverse the field structure over a magnetic path extending from the north pole of the core 6! by way of the leg Eta, the leg ill), the armature 61, the leg 62b and the leg 62a to the south pole of the core. Also the permanent bar magnet sets up a magnetic fiux which traverses two parallel magnetic paths. One of these parallel magnetic paths extends from the north pole of the permanent bar magnet T? by way of a portion of the armature 87, the legs 52?; and. 52a, a portion of the core 65, the legs Sid and Blb and another portion of the armature 6! to the south pole of the permanent bar magnet. The other of these parallel magnetic paths extends from the north pole of the permanent bar magnet H by way of the adjacent portion of the armature E! to the south pole of the permanent bar magnet, this magnetic path constituting a short-circuit-ing magnetic path for the permanent bar magnet. It is noted that the permanent bar magnet 77 has a sufiiciently high permeability that a considerable magnetic fiux produced thereby traverses the first-mentioned parallel magnetic path in spite of the fact that the second-mentioned parallel magnetic path constitutes a short-circuiting magnetic path for the permanent bar magnet. Also, it is noted that the magnetic flux produced by the polarizing winding '15 traverses :the magnetic field structure in the same direction as the magnetic flux produced by thepermanentbar magnet 11. These accumulative magnetic fluxes are effective to cause the armature 6'!" to be attracted to the leg iilb of the field element thereby to bias the armature t! in acountcrclockwise direction about the pivot pin 2% away from the pole face Eda and into engagement with the leg 6111. Also, the armature 67 is biased away from the pole lace 50a and into engagement with the-leg tib due to the resiliency of the contact spring H. Accordingly, when the control device occupies a normal or non-operated position, the armature [H is biased away from the pole face Eta of the core Gil into engagementwith the leg 85?) of the field element SI.

The terminals of the operating winding are connected to a suitable source of direct current supply, thereby to cause this winding to be ener ized. When the operating winding is thus energized, amagnetic flux is set up in the core 8%? which causes the end thereof, adjacent the pole face Bria, to assume a predetermined polarity Yand the portion thereof, adjacent the leg 65a, to assume axpredetermined polarity X, the polarities X and Y being respectively north and south poles when the operating winding is energized with a current of one polarity, and the polarities X and Ybeing respectively south and north poles when the operating winding is energized with a current of the opposite polarity. When the operating winding Hi is energizled with a current of one polarity so that the polarity Y of the core to is a north pole, a magnetic fiux traverses the field structure over a magnetic path extending from the north pole Y of the core 60 by way or the armature t1, the legs 52b and 52a of the field element 62 and the portion of the core iii! disposed between the legs 62a and tile to the south pole X of the core. It I is noted that this magnetic flux traverses the core till in the same direction as the magnetic flux produced by the polarizing winding 16. These accumulative magnetic fluxes are effective to cause the armature 61 to be attracted to the pole face 68a of the core 6'43, thereby to rotate the armature ii? in a clockwise direction about the pivot pin 66. When the armature 61 is rotated in a clockwise direction about the pivot pin the insulating button (59 carried by the arm E33 moves the resilient contact spring H into engagement with the contact spring It,

thereb-yto complete the electric circuit including i this pair of contact springs.

:It is noted that when the armature E1 occupies a non-operated position the polarizing winding it produces. a magnetic flux which is effective to bias the armature ii! in a counterclockwise direction about'the pivot pin 56 away from the pole face and into engagement with. the legtib of the field element 8!. On the other hand, when the armature 6? is rotated in a clockwise direction about the pivot pin 6'5 away from the leg-bib of the field elementfil and intc'engagement with'the pole face 69a, the flux produced by the polarizing winding 16 is effective to bias the armature .61 into engagement with the-pole face-Eta away from the leg 6H; of the 'field element 6|. Thus, the polarizing winding iil produces a flux which biases the armature t1 toward the poleiace 6M ortoward the leg Bl'b of the field element lil depending upon .the one of these elements toward which the armature BT15 moved.

When the operating winding 15 is deenergized the flux produced by the polarizing winding 76 is insufiicient to retain the armaturel"! in its operated position against the bias of the resilient contact spring H. Accordingly, the armature 6'! is rotated in a counterclockwise direction about the pivot pin 66 away from the pole face Gila and into engagement with the leg Bio of the field element 6!. At this time the device occupies a non-operated position.

On the other hand, when the operating winding 15 is energized with a current of the opposite polarity so that the polarity Y of the core [ill is a south pole, a'magnetic flux is produced which traverses the field structure over a magnetic path extending from the north pole X of the core 65} by way of the portion of the core 60 disposed'between the leg 52a of the field element 62 and the leg tin of the field element til, the legs 62c and 62b of the field element 62 and the armature 6'1 to the south pole Y of the core 60. It is noted that this magnetic fiux'traverses the magnetic field structure in a direction opposite to that of the magnetic flux produced by the polarizing winding it and the permanent bar magnet ll. These opposing magnetic fluxes are ineffective to cause the armature 61 to be attracted to the pole face 653a of the core 60.. Thus, the armature 6'! is not rotated in a clockwise direction about the pivot pin 55 to move the contact spring ll into engagement with the contact spring H3. Thus, it will be understood that this control device is of the polarized type and is operative only in the event the operating winding "Hi thereof is energized with a current of a predetermined polarity, the position of the armature til with respect to the core being controlled in accordance with the algebraic sumv of the fluxes traversing these elements.

Moreover, it is noted that when the operating winding 15 is energized with a current of the opposite polarity effective to cause the polarity Y of the core 68 to be a south pole, the magnetic flux traversing the armature 61 of the field structure at this time is by-passed around the permanent bar magnet 'l'! by way of the portion of the armature ii! adjacent the perma nent bar magnet 11. Thus, this magnetic flux opposing the magnetic fiuxes produced by the polarizing winding 16 and the permanent bar magnet H is not forced through the permanent bar magnet. Accordingly, there is substantially no tendency for the permanent bar magnet 11 to become deenergized when the fluxes produced by the operating winding 15 and those produced by the polarizing winding 15 and the permanent bar magnet Tl traverse the field structure in opposite directions or oppose each other. Hence, the portion of the armature 61 disposed adjacent the permanent bar magnet 11 is effective to prevent demagnetization of the permanent bar magnet when the operating winding 15 is energized with a current of the opposite polarity effective to cause this winding to produce a flux in the field structure in opposition to the fluxes produced therein by the polarizing winding H3 and the permanent bar magnet H.

In Figs. 7 and 8 of the drawing a further modified form of the control device is shown which comprises a magnetic field structure including a field element or core 80, a substantially U- shaped field element ill, one leg 8la of which is secured to the core 88 intermediate the ends thereof, and a substantially L-shaped field element 82, one leg 82a of which is secured to one end of the core by a screw 83. The other leg 81b of the field element 8| is arranged in spaced relationship with respect to a pole face indicated at 80a of the core 80 and the other leg 82?) of the field element 82 extends substantially parallel to the core 80 and carries a bracket 84 adjacent the outer end thereof, the bracket being secured to the leg 8% by a screw 85. The bracket 84 is provided with two upwardly and outwardly extending arms 8 la arranged in spaced parallel relationship and between which a pin 86 extends. An armature element 8'! is arranged between the pole face 80a of the core 80 and the leg 8lb of the field element 8! and is provided with two upwardly extending arms Bla arranged in spaced parallel relationship which are pivotally secured to the pin 85. Also, the armature 81 carries a rearwardly extending arm 88 provided with an insulating button 89 disposed on the outer end thereof. Apparatus comprising a contact spring assembly including a pair of cooperating contact springs 99 and 9! is secured to the leg 82b of the field element 82 by an arrangement comprising two screws 92 and a clamping washer 93. The contact springs 98 and 9! are insulated from each other and from the clamping washer 93 and the leg 82b of the field element 82 by a number of insulating plates 94, one of these insulating plates being arranged between each two of these elements.

The insulating button 89 disposed on the outer end of the arm 88 directly engages the contact spring 9! and is adapted to move this contact spring into engagement with the contact spring 80 in order to complete an electric circuit including the pair of contact springs 50 and 9| when the armature 81 is rotated in a clockwise direction, as viewed in Fig. 7, about the pivot pin 85. Also, it is noted that the contact spring BI is formed of resilient material and is biased away from the contact sprin 96, thereby to interrupt the electric circuit including this pair of contact springs and to bias the armature 81 in a counterclockwise direction about the pivot pin 86 away from the pole face 80a into a normal position.

An operating winding and a polarizing winding, respectively indicated at 95 and 96, are electromagneticaliy associated with the core 81], the operating winding 95 being associated with the core 80 between the pole face 89a and the leg 81a of the field element 8|, and the polarizing winding 96 being associated with the core 80 between the leg Bla of the field element 8! and the leg 82a of the field element 82.

A permanent bar magnet 91 is directly secured in intimate contact with the edge of the field el ment 8| intermediate the legs 8 la and Gib thereof by an arrangement comprisin a strap 38 and a screw 99. The permanent bar magnet 87 is formed of a material having relatively high magnetic permeability and retentivity such, for example, as the alloys previously named. The permanent bar magnet 97 is so arranged that a south pole thereof is directed toward the leg am of the field element BI and a north pole thereof is di rected toward the leg 8H9 of the field element 8!.

The terminals of the polarizing winding 96 are connected to a suitable source of direct current supply, thereby to cause this winding to be energized. The polarity of this source of direct current supply is such that when the polarizing winding 96 is thus energized, a magnetic fiux is set up in the core 80 which causes the portion thereof adjacent the leg Bid to assume the polarity of a north pole and the portion thereof adjacent the leg 82a to assume the polarity of a south pole, thereby to cause a magnetic flux to traverse the field structure over a magnetic path extending from the north pole of the core 80 by way of the leg Bic, the leg Bib, the armature 81, the leg 8% and the leg 82a to the south pole of the core. Also, the permanent bar magnet sets up a magnetic fiux which traverses two parallel magnetic paths. One of these parallel magnetic paths extends from the north pole of the permanent bar magnet 9'! by way of the leg 8H2 of the field element 8!, the armature 81, the legs 82b and 82a of the field element 82, a portion of the core 86 and the leg 35a of the field element 8| to the south pole of the permanent bar magnet. The other of these parallel magnetic paths extends from the north pole of the permanent bar magnet 97 by way of the adjacent portion of the field element 8| to the south pole of the permanent bar magnet, this magnetic path constituting a short-circuiting magnetic path for the permanent bar magnet. It is noted that the permanent bar magnet 91 has a sufficiently high permeability that a considerable magnetic flux produced thereby traverses the first-mentioned parallel magnetic path in spite of the fact that the second-mentioned parallel magnetic path constitutes a short-circuiting magnetic path for the permanent bar magnet. Also, it is noted that the magnetic flux produced by the polarizing winding 98 traverses the magnetic field structure in the same direction as the magnetic flux produced by the permanent bar magnet 91. These accumulative magnetic fiuxes are effective to cause the armature 81 to be attracted to the leg Blb of the field element 8|, thereby to bias the armature 81 in a counterclockwise direction about the pivot pin 86 away from the pole face 38a and into engagement with the leg Bib. Also, the armature 81 is biased away from the pole face 89a and into engagement with the leg 811) due to the resiliency of the contact spring 9!. Accordingly, when the control device occupies a normal or non-operated position, the armature 81 is biased away from the pole face 89a of the core 313 into engagement with the leg 8lb of the field element 8!.

The terminals of the operating winding 95 are connected to a suitable source of direct current supply, thereby to cause this winding to be energized. When the operating winding is thus energized, a magnetic fiux is set up in the cor 80 which causes the end thereof, adjacent the pole face 813a, to assume a predetermined polarity Y and the portion thereof, adjacent the leg Bid, to assume a predetermined polarity X, th polarities X and Y being respectively north and south poles when the operating winding is energized with a current of one polarity, and the polarities X and Y being respectively south and north poles when the operating winding is energized with a current of the opposite polarity. When the operating winding 95 is energized with a current of one polarity so that the polarity Y of the core 80 is a north pole, a magnetic flux traverses the field structure over magnetic path extending from the north pole Y of the core 80 by way of the armature 81, the legs 82b and 82a of the field element 82, the portion of the core 8t disposed between the legs 82a and 81a to the south pole X of the core. It is noted that this magnetic flux traverses the core 80 in the same direction as the magnetic flux produced by the polarizing winding 96.

These accumulative magnetic fluxes are effective to cause the armature B1 to be attracted to the pole face 89a of the core 88, thereby to rotate the armature ET in a clockwise direction about the pivot pin 85. When the armature 81 is rotated in a clockwise direction about the pivot pin 85, the insulating button 89 carried by the arm 88 moves the resilient contact spring 9! into engagement with the contact spring 90, thereby to complete the electric circuit including this pair of contact springs.

It is noted that when the armature i1 occupies a non-operated position, the polarizing winding 96 produces a magnetic flux which is effective to bias the armature 87 in a counterclockwisedirection about the pivot pin 86 away from the pole face 89a and into engagement with the leg Gib of the field element ii i. On the other hand, when the armature 81 is rotated in aclockwise direction about the pivot pin 86 away from the leg 8i?) of the field element Si and into engagement with the pole face 3%, the flux produced by the polarizing winding 96 is eifective to bias the armature 81 into engagement with the pole face iiiia away from the leg Bib of the field element 8i. Thus, the polarizing winding 96 produces a fiux which biases the armature 8? toward the pole face title or toward the leg fiib of the field element 3i depending upon the one of these elements toward Which the armature 81 is moved.

When the operating winding 95 is energized with a current of one polarity effective to cause the polarity Y of the core 89 to become a north pole, a magnetic flux also traverses the field structure by way of a magnetic path extending from the north pole Y of the core Si) by way of the armature 8?, the leg iiib and the leg 85a to the south pole X of the core 80. It is noted that this magnetic flux produced by the operating winding 25 traverses the field element Si in a direc- Accordingly, there is substantially no tendency for the permanent bar magnet 91 to become demagnetized when the fluxes produced by the operating winding 95 and the permanent bar magnet 91 traverse the field structure in opposite directions or oppose each other. portion of the field element ill disposed adjacent the permanent bar magnet 9! is effective to prevent demagnetization of the permanent bar magnet when the operating winding is energized with Hence, the j a current of one polarity effective to cause the armature 67 to be rotated in a clockwise direction about the pivot pin 86.

When the operating winding 95 is deenergized. the flux produced by the polarizing winding 95 traversing the field structure is insufficient to retain the armature B! in its operated position against the bias due to the resilient contact spring 9| and the bias produced by the permanent bar magnet S'i. The bias produced by the permanent bar magnet 9'5 is caused by a flux produced thereby which traverses a magnetic path extending from the north pole of the permanent bar magnet 97 by way of the leg Bib of the field element 8|, the armature 87, the legs 82b and 82a disposed between the leg 82a of the field element 82 and the leg Elia of the field element 8! and the leg 8m of the field element 8! to the south pole of the permanent bar magnet.

Thus, the armature 8'! is positively biased in a counterclockwise direction about the pivot pin 86 by the permanent bar magnet 9'! and the resilient contact spring ti, when the operating winding is deenergized. Accordingly the armature 81 is rotated in a counterclockwise direction about the pivot pin 36 away from the pole face 80a into engagement with the leg 8ib of the field ele ment 8 i. At this time the device occupies a nonoperated position.

On the other hand when the operating winding 95 is energized with a current of the opposite polarity so that the polarity Y of the core 80 is a south pole, a magnetic fiux is produced which traverses the field structure over a magnetic path extending from the north pole X of the core 8% by way of the portion of the core 89 disposed between the leg 82a of the field element 82 and the leg am of the field element 8!, the legs 82a and 82b of the field element 82 and the armature 81 to the south pole Y of the core. It is noted that this magnetic flux traverses the magnetic field structure in a direction opposite to that of thre magnetic fluxes produced by the polarizing winding 96 and the permanent bar magnet 91. These opposing magnetic fiuXes are ineifective to cause the armature 81 to be attracted to the pole face Mia of the core Bii. Thus, the armature ill is not rotated in a clockwise direction about the pivot pin 86 to move the contact spring 9i into engagement with the contact spring 90. Thus, it will be understood that the control device is of the polarized type and is operative only in the event the operating winding 95 thereof is energized with a current of a predetermined polarity, the, position of the armature 81 with respect to the core 8! being controlled in accordance with the algebraic sum of the fluxes traversing these elements.

While there have been described what are at present considered to be the preferred embodiments of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

Wh at is claimed is:

l. A control device comprising a field structure including a permanent magnet, first and second field elements, and a movable armature disposed between said field elements; and an operating winding and a polarizing winding electromagnetically associated with said field structure; said field structure and said windings constituting means including said permanent magnet for normally restraining said armature toward said second field element, means including said operating winding when energized with current of a predetermined polarity for moving said armature toward said first field element, means including said polarizing winding when energized for biasing said armature toward the one of said field elements toward which it is moved by one of said two first-mentioned means, and means including said permanent magnet for returning said armature toward said second field element against the bias of said last-mentioned means after said operating winding is deenergized.

2. A control device comprising a magnetic field structure including a first field element, a secof the field element 82, the portion of the core 80 35 0nd field element carried by said first field element intermediate first and second ends thereof and provided with an end disposed in spaced relation with respect to the first end of said first field element, a third field element supported by said first field element adjacent the second end thereof, a movable armature carried by said third field element and extending between the first end of said first field element and the end of said second field element, and a permanent magnet carried by said second field element; an operating winding electromagnetically associated with said first field element adjacent the first end thereof; and a polarized winding electromagnetically associated with said first field element adjacent the second end thereof; said field structure and said windings constituting means including said permanent magnet for normally restraining said armature toward the end of said second field element, means including said operating winding when energized with current of a predetermined polarity for moving said armature toward the firs-t end of said first field element, means including said polarizing winding when energized for biasing said armature toward the end of the one of said field elements toward which it is moved by one of said two first-mentioned means, and means including said permanent magnet for returning said armature toward the end of said second field element against the bias of said last-mentioned means after said operating winding is deenergized.

3. A control device comprising a field structure including first and second field elements, a permanent magnet carried by one of said field elements, and a movable armature disposed between said field elements; and an operating winding and a polarizing winding electromagnetically associated with said field structure; said field structure and said windings constituting means including said permanent magnet for normally restraining said armature toward said second field element, means including said operating winding when energized with current of a predetermined polarity for moving said armature toward said first field element, means including said polarizing winding when energized for biasing said armature toward the one of said field elements toward which it is moved by one of said two first-mentioned means, means including said permanent magnet for returning said armature toward said second field element against the bias of said last-mentioned means after said operating winding is deenergized, and means including the portion of said one field element adjacent said permanent magnet for preventing demagnetization of said permanent magnet when said operating winding is energized to produce a flux in said one field element in opposition to the fiux produced therein by said permanent magnet.

4. A control device comprising a field structure including first and second field elements, a permanent magnet carried by said second field element, and a movable armature disposed between said field elements; and an operating winding and a polarizing winding electromagnetically associated with said field structure; said field structure and said windings constituting means including said permanent magnet for normally restraining said armature toward said second field element, means including said operating winding when energized with current of a predetermined polarity for moving said armature toward said first field element, means including said polarizing winding when energized for biasing said armature toward the one of said field elements toward which it is moved by one of said two firstmentioned means, means including said permanent magnet for returning said armature toward said second field element against the bias of said last-mentioned means after said operating winding is deenergized, and means including a portion of said second field element for preventing demagnetization of said permanent magnet when said operating winding is energized to produce a flux in said second field element in opposition to the flux produced therein by said permanent magnet.

5. A control device comprising a magnetic field structure including a movable armature, a permanent magnet secured to said armature; and an operating winding and a polarizing winding electromagnetically associated with said field structure; said field structure and said windings constituting means for normally restraining said armature toward a predetermined position, means including said permanent magnet and said polarizing winding when energized for preventing movement of said armature away from said predetermined position when said operating winding is energized with current of one polarity, and means for causing movement of said armature away from said predetermined position when said operating winding is energized with current of the opposite polarity; said permanent magnet being carried by said armature and so secured thereto that both of the magnetic poles of said permanent magnet are in contact with said armature, whereby the portion of said armature adjacent to said permanent magnet constitutes a shunt for said permanent magnet for preventing demagnetization of said permanent magnet when said operating winding is energized to produce a fiux in a predetermined portion of said field structure in opposition to the fiuX produced therein by said permanent magnet.

6. A control device comprising a field structure including first and second field elements, a permanent magnet secured to one of said field elements, and a movable armature disposed between said field elements; and an operating winding and a polarizing winding electromagnetically associated with said field structure; said field structure and said windings constituting means for normally restraining said armature toward a predetermined one of said field elements, means including said permanent magnet and said polarizing winding when energized for preventing movement of said armature away from said predetermined one field element when said operating winding is energized with current of one polarity, and means for causing movement of said armature away from said predetermined one field element when said operating winding is energized with current of the opposite polarity; said permanent magnet being carried by said one field element and so secured thereto that both of the magnetic poles of said permanent magnet are in contact with said one field element, whereby the portion of said one field element adjacent to said permanent magnet constitutes a shunt for said permanent magnet for preventing demagnetization of said permanent magnet when said operating winding is energized to produce a flux in said one field element in opposition to the flux produced therein by said permanent magnet.

CARL P. CLARE. IRVIN W. COX. 

